1. Technical Field
The present invention relates to a bonding method and a method of manufacturing a microchannel device.
2. Related Art
A microchannel device has recently been used for analysis of a liquid sample. The microchannel device is configured to pass samples or other liquids through a microchannel to cause chemical or biochemical reactions in the microchannel so that a detection target substance included in a sample is detected.
A microchannel device is typically configured by stacking a plurality of substrate members so that a channel is formed between two adjacent substrate members. The two substrate members which form the channel are typically bonded by, for example, an adhesive tape. Also, there is known a channel in which two substrate members are bonded by ultrasonic welding in order to increase a sealing property of the channel (e.g., See, Patent Literature 1 (JP-A-2011-161578)).
In a method of manufacturing a microchannel device disclosed in Patent Literature 1, two substrate members (a substrate member formed with a protruding portion and a stopper and a flat substrate member) are stacked and applied with ultrasonic vibration under a predetermined pressurization condition so that the protruding portion is gradually welded on the surface of the flat substrate member. In this method, when the stopper and the flat substrate member come in contact with each other as the welding proceeds, the ultrasonic vibration is stopped, and a space sandwiched between the protruding portion and the substrate member is formed as a channel.
There are known various technologies for ultrasonic bonding. Patent Literature 2 (JP-A-3-183527) discloses a method of allowing bonding to be performed within a short time without reducing a bonding strength by gradually decreasing amplitude of ultrasonic waves from initiation of bonding when semiconductor chips are bonded by using an adhesive.
Patent Literature 3 (JP-A-2006-204983) discloses a method of easily and inexpensively manufacturing a microreactor in which a condition of a member pressing pressure with respect to oscillation energy and oscillation time is set to a desired value in ultrasonic oscillation.
As disclosed in Patent Literature 1, in a method of defining a height of a channel by using a stopper, when the stopper and a flat substrate member come in contact with each other in a larger area than a contact area between a protruding portion and the flat substrate member, a resistance between substrate members is increased. As a result, energy of ultrasonic oscillation is hardly transmitted to the protruding portion so that the welding of the protruding portion may be stopped.
Accordingly, in order to make the height of the microchannel uniform, it is required to bring substrate members in contact with each other at once over the all locations of a stopper. However, a microchannel device has one side length on the order of centimeters. Accordingly, the substrate members may not come in contact with each other at once over the all locations of the stopper due to, for example, warpage of the substrate members. In such a case, due to a resistance increase caused by contact between the stopper and the substrate member, welding of a protruding portion is stopped early. Accordingly, the height of the microchannel may not be uniform.
Patent Literatures 1 to 3 do not consider a problem in that welding of a protruding portion is early stopped by using a stopper, and the height of a channel becomes non-uniform, and thus do not disclose a means for solving the problem.
The present invention has been made in view of the above described circumstances, and an object thereof is to provide a bonding method in which a protruding portion for bonding two members to each other through ultrasonic welding may be welded without non-uniformity in height over the entire length of the protruding portion, and a method of manufacturing a microchannel device which may perform a control of a channel space with high precision.
An aspect of the present invention provides a bonding method of bonding a first substrate member to a second substrate member, the method comprising ultrasonically welding a protruding portion extending on a surface of the first substrate member to a surface of the second substrate member by applying ultrasonic vibration to the first substrate member in a state where a for portion of the protruding portion is pressed against the surface of the second substrate member, wherein a protruding stopper portion for stopping welding is provided on the surface of the first substrate member formed with the protruding portion, or on the surface of the second substrate member to come in contact with the protruding portion in the pressed state, to be disposed around the protruding portion in the pressed state, and the ultrasonically welding includes a first process for applying ultrasonic vibration at amplitude as a first value to the first substrate member, and a second process for applying ultrasonic vibration to the first substrate member at amplitude as a second value lower than the first value after the first process.
Another aspect of the present invention provides as manufacturing method of manufacturing a microchannel device in which a channel is formed between a first substrate member and a second substrate member which are bonded to each other, the method comprising: ultrasonically welding a protruding portion extending on a surface of the first substrate member to a surface of the second substrate member by applying ultrasonic vibration to the first substrate member in a state where a top portion of the protruding portion is pressed against the surface of the second substrate member, the protruding portion corresponding to an edge of the channel, wherein a protruding stopper portion for stopping welding is provided on the surface of the first substrate member formed with the protruding portion, or on the surface of the second substrate member to come in contact with the protruding portion in the pressed state to be disposed around the protruding portion in the pressed state, the ultrasonically welding includes a first process for applying ultrasonic vibration at amplitude as a first value to the first substrate member, and a second process for applying ultrasonic vibration to the first substrate member at amplitude as a second value lower than the first value after the first process.
According to the present invention, there is provided is bonding method in which a protruding portion for bonding two members to each other through ultrasonic welding may be welded without non-uniformity in height over the entire length of the protruding portion, and a method of manufacturing as microchannel device which may perform a control of as channel space with high precision.